Field of the Invention
The present invention relates to an adhesive composition, a laminate, and a stripping method.
Background Art
Products such as a mobile telephone, digital AV equipment, an IC card, and the like have been improved to have more sophisticated functions. This gives rise to an increase in demand for semiconductor silicon chips (hereinafter, referred to as chips) provided in the products to be downsized and thinned so that the chips can be highly integrated in a package. For example, for an integrated circuit in which a plurality of chips are provided in one package, such as a chip size package (CSP) or an multi-chip package (MCP), there is a demand for the chips to be thinned. In order to highly integrate the chips in the package, it is necessary to thin the chips to a thickness in a range of 25 μm to 150 μm.
By a grinding process, semiconductor wafers (hereinafter, referred to as wafers) which serve as bases for the respective chips are thinned. This, however, weakens the strength of the wafers, and cracks and warp is likely to occur on the wafers. In addition, the wafers weakened in strength through the thinning are difficult to be carried automatically and need to be carried manually. As can be understood from this, handling of the wafers is troublesome.
As a countermeasure, a wafer handling system has been developed. According to the wafer handling system, a plate called a support plate, which is made from glass, hard plastic, or the like, is bonded to the wafers to be thinned through an adhesive layer so that the strength of the wafers is maintained, and occurrence of cracking and warping appearing on the wafer are prevented. Because the strength of the wafers can be secured by the wafer handling system (WHS), it is possible to automatically carry the semiconductor wafers subjected to the thinning process.
As a method for manufacturing semiconductor chips in which a support is bonded to a semiconductor wafer, the semiconductor wafer is processed, and then, the support is separated therefrom, a method described in JP-A-2004-64040 (publication date: Feb. 26, 2004) is known. In the method described in JP-A-2004-64040, a light-transmitting support and a semiconductor wafer are bonded through a photothermal conversion layer and an adhesive layer provided on the support side, the semiconductor wafer is processed, and then, radiant energy is radiated from the support side to decompose the photothermal conversion layer, whereby the semiconductor wafer is separated from the support.